This invention relates generally to an adjustable bracket, and more particularly to such a bracket for use with a rail car coupler for effecting vertical adjustment of a coupler carrier thereof.
As discussed in the aforementioned application, the coupler extending outwardly of opposite ends of a typical rail car has a shaft extending along the centerline of the draft gear of the car, the shaft being mounted for longitudinal as well as vertical and transverse movements so as to permit continued interengagement during car travel with a similar coupler of an adjacent car. Such a coupler shaft typically rests on a transverse coupler carrier having a wear plate thereon so as to minimize wear. The coupler carrier is supported at opposite ends by carrier brackets which are normally fixedly mounted to side plates on the rail car.
The centerline of a freight car coupler is nominally set at 341/2 inches above the rail. The Interchange Requirements of the Association of American Railroads (AAR) presently require coupler heights for empty cars to be a minimum of 321/2 inches and a maximum of 341/2 inches measured from the top of the rail to the center of the face of the coupler knuckle. For loaded cars coupler heights of a minimum of 31 1/2 inches and a maximum of 331/2 inches are required and, where possible, adjustments are suggested to be made when the car is empty. This is a typical standard set for all freight cars by the AAR.
When it is desired to adjust the coupler height upwardly in order to comply with the above-noted coupler heights, due to excessive wear of the carrier member wear plate or because the standard coupler height was not maintained by the freight car manufacturer, shims are customarily inserted between the coupler carrier wear plate and the coupler shaft. These coupler carrier shims are required by the AAR to be of a minimum 1/4 inch thickness, and may be flat, L-shaped or U-shaped in cross-section so as to be slipped over the coupler carrier wear plate. The coupler must be elevated as by means of a jack or the like to its upper limit in order to carry out this standard procedure. The shim may then be installed beneath the coupler shaft and welded or otherwise secured in place over the wear plate.
The height of the rail car coupler may be adjusted by placing the coupler in the proper alignment with the draft gear of the car using one of the aforedescribed shims where necessary. If less than 1/4 inch is required for the shim, realignment is not necessary. Also, where the coupler is in proper alignment and the minimum coupler height has not resulted, further adjustment must be made at the truck springs, center plates or journal boxes of the car. The truck spring shims must be of hardwood of not less than 5/8 inch thickness, or steel of not less than 1/4 inch. On the other hand, when the coupler is in proper alignment and height, but is sagging by one inch or more, it must be adjusted by means of the shims as aforedescribed.
It is important to note that the coupler adjustments as described above provide only vertically upward adjustment but no vertically downward adjustment.
It has been found that vertically downward adjustment of the coupler height is oftentimes required especially for newly built rail cars. During the construction of such new cars, the extreme dimensional tolerances in wheels, truck side frames and bolsters, center plates and fabricated roll sections are accumulated to the extent that the coupler height becomes unpredictable. The car builders repeatedly strive to adhere to the AAR requirements set for the coupler height, but are not always successful. Oftentimes, newly built cars are delivered with a coupler height of 351/2 inches. This creates much agony for the car builder and the railroad since the Federal Railroad Administration inspectors may very well condemn the car for the reason that the coupler height for the empty new car at 351/2 inches and the loaded car at a minimum of 311/2 inches would result in a 4 inch differential. Normal vertical oscillations of the car over the road could therefore cause the mated couplers between the cars to become disengaged.
Also, there is a trend toward the use of hardened wear plates located under the coupler shaft of expensive wear resistant steel such as cast manganese. Therefore, introduction of a mild steel shim would only destroy the wear potential of the manganese, or equivalent, coupler carrier wear plate.
The only known coupler height adjuster other than the use of shims is a trunnion hung device having rotated cam wheels at each side. This results in a swing hanger effect under the coupler which is oftentimes undesirable from the standpoint of effectiveness and safety.